Mechanisms for inducing motion from a driving member, such as a shaft or piston, to a driven member, such as another shaft or axle, are widespread throughout many technical areas.
In an underground environment, such as in an oil or gas wellbore, a variety of technical operations are carried out which involve moving and placing a variety of pieces of equipment in a number of ways. Drive mechanisms for use in such an underground environment would be highly useful. However, this environment presents significant engineering constraints restricting the design of such devices. It is typically the case that a general lack of space restricts the size such devices can take, and the relative difficulty of obtaining power to drive such a mechanism means that only low power devices are practical. Additionally, it is often desirable that the drive mechanism be disposed in the downhole location such that fluids or the like may pass through a section of wellbore proximal to the drive mechanism. Similar constraints may be associated with drive mechanisms for use on pipelines.
If additional constraints are present, such as requiring a high torque and/or requiring fine control, which control may be in the range of few revolutions per minute, then design options become severely restricted. Known mechanisms fail to adequately satisfy all of these requirements. There is therefore a need for an improved drive mechanism, particularly for use in a downhole environment and/or for operation on pipelines.